The term muster designates the process or event for the of accounting for members in a military unit. Within the United States Army Reserve

United States Army Reserve

The United States Army Reserve is the federal reserve force of the United States Army. Together, the Army Reserve and the Army National Guard constitute the reserve components of the United States Army....

, it is an annual event used for screening purposes.

Historical

In Tudor

Tudor period

The Tudor period usually refers to the period between 1485 and 1603, specifically in relation to the history of England. This coincides with the rule of the Tudor dynasty in England whose first monarch was Henry VII...

 England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

, musters were periodic assessments of the availability of local militia

Militia

The term militia is commonly used today to refer to a military force composed of ordinary citizens to provide defense, emergency law enforcement, or paramilitary service, in times of emergency without being paid a regular salary or committed to a fixed term of service. It is a polyseme with...

 to act as a defence force when needed. To some extent, the system was an outdated remnant of the feudal

Feudalism

Feudalism was a set of legal and military customs in medieval Europe that flourished between the 9th and 15th centuries, which, broadly defined, was a system for ordering society around relationships derived from the holding of land in exchange for service or labour.Although derived from the...

system where local lords had their own armies, which they provided for the King as required.

This practice of inspections led to the coining of the English idiom pass muster, meaning being sufficient.